MIAMI -- Concussions are the hot topic in the NFL right now, with increased concern about the brain health of football players once their careers are over. NFL commissioner Roger Goodell has made it clear he is concerned about the issue and has implemented several directives, including return-to-play rule changes.

Congressional members have expressed concern about the issue for the general public as well. In October, a panel of House Judiciary Committee members held hearings related to head injuries in football, asking medical experts, equipment manufacturers, former players and administrators of college and youth sports to explain how they are working to address the issue. The discussion about the risks of long-term brain damage after repeated impacts has led to a broader conversation about how concussions affect athletes of all ages.

There appears to be little in the medical world that is definitive when it comes to this subject, but it seems that everyone agrees: Concussions are serious injuries that need to be properly recognized and appropriately managed to avoid catastrophic consequences, particularly in the developing brain.

The Centers for Disease Control and Prevention reports a sports-and-recreation-related concussion rate of approximately 3.8 million per year. With millions of youths engaged in a variety of sports, this issue has become a matter of national public health and safety. The discussion about concussions raises a number of questions. Here are some of those questions and their answers:

What exactly is a concussion?

Washington running back Clinton Portis suffered a concussion in November. He has said he expects to be back with the team for 2010. Todd Kirkland/Icon SMI

A concussion is a form of brain injury. When the head accelerates through space, the brain also accelerates within the skull. The shear forces to which the brain is subjected during violent movement can result in damage to nerve cells throughout. Technically speaking, a concussion itself is an electroneurophysiological event. As a result of damage to nerve cells within the brain, the brain temporarily fails to process information in a normal way. The injury can occur as a result of a blow to the head, but concussions also can be noncontact injuries -- think severe whiplash. An individual might lose consciousness, but not necessarily. In fact, some very serious concussions happen without the patient ever losing consciousness.

Is every concussion the same?

No. Concussions are like snowflakes; no two are exactly alike. Concussions represent a spectrum of brain injury. Although all are serious because they signify injury to the brain, their effects can vary widely. Some concussions result in short-term mild symptoms; others lead to more severe symptoms that can last for weeks, months or even permanently.

Is there any imaging device that can confirm a concussion?

No. MRIs or CT scans, although critical in identifying skull fractures or bleeding within the brain, are not necessarily helpful in evaluating a concussion. After a concussion, imaging devices might not show structural changes or areas of deficit in the brain. Medical practitioners must rely primarily on the presence of signs and symptoms to support the diagnosis of a concussion.

What are those signs and symptoms?

If an athlete loses consciousness, he or she has suffered a concussion. But as mentioned earlier, a concussion can occur without a loss of consciousness. Other signs (things that others can observe) can include memory loss of events before or after the incident, confusion, slurred speech, vacant staring or disorientation. The most common symptoms (things that the patient experiences) are headache, nausea, vomiting and dizziness. Other complaints include sensitivity to light, blurry vision, irritability or difficulty concentrating.

Beyond signs and symptoms, are there any tools to evaluate concussions?

Because concussions impact the brain's ability to process information, often in subtle ways, a key component of the evaluation process is neurocognitive testing. This involves a battery of tests to evaluate things such as brain processing speed, memory and reaction time. Testing done before an athletic season can provide baseline data against which future tests after an injury can be measured. Even when a player reports the absence of symptoms and there are no observable signs, a neurocognitive test can show a deficit in information processing, indicating that the brain has not yet fully recovered.

The test, which the NFL and MLS use for all their athletes, is ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing), which was developed in the early 1990s by Drs. Mark Lovell and Joseph Maroon of the University of Pittsburgh Medical Center. ImPACT is the most widely used test, but Maroon, a neurosurgeon at UPMC and team neurosurgeon for the Pittsburgh Steelers, said this type of testing is still not reaching nearly enough youth athletes. "There are 18,000 high schools in the United States, but there is no form of neurocognitive testing in 16,000 of them," he said. "We have a long way to go."

As it stands, the only way to really assess the seriousness of a concussion is after the symptoms have gone away. If an athlete fully recovers within hours, the injury was mild. If an athlete experiences symptoms weeks or even months later, the injury was more substantial. There is no way to know immediately with any degree of certainty just how significant the impact on the brain is with any single concussion, so it makes sense to treat athletes who suffer these injuries with uniform and consistent guidelines to optimize their safety.

What is the treatment for a concussion?

One of the key elements in assisting the brain to recover after a concussion is rest. It is important to refrain from athletic activity and to rest the brain from strenuous cognitive or mental activity such as reading, writing, watching TV or working on the computer. For a young athlete, this might mean time away from the classroom as well as the playing field.

When is it OK for an athlete to return to play?

This is the most hotly debated question right now. Recovery occurs at different rates, so there is no universal timetable. An athlete must be free of all signs and symptoms at rest and be free of all signs and symptoms with physical activity. In the NFL, a player must demonstrate that his neurocognitive function has returned to preinjury levels as established by the ImPACT test. Many high schools or other youth programs do not have any form of neurocognitive testing in place. The hope is that this will change with increased education and awareness. The decision to return to play should rest in the hands of a licensed medical provider specifically trained in the area of concussion evaluation and management. This frees athletes, coaches and family members from making what really constitutes a medical judgment.

Why is this issue so critical for youth athletes?

Cameron Schlegel, a senior at Manvel (Texas) High School, suffered concussions during football games in October and November. Upon advice of school medical staff and his doctor, he did rehab before his health was restored. He is with his mother, Trish. AP Photo/Bob Levey

The developing brain is more susceptible to serious injury after a concussion. The developing brain is also more at risk for second-impact syndrome, which occurs when an athlete suffers a second blow to the head before he or she has fully recovered from an initial concussive event. In these instances, the consequences can be catastrophic, resulting in permanent brain injury or even death. In addition, because young athletes are under the age of legal decision-making, they need others to advocate for their well-being. Legislation such as the Zackery Lystedt Law helps take the decision of when it is safe to return to play out of the hands of non-medical providers. The format of the legislation allows for individual medical evaluation, which is essential with these types of injuries.

What is the Zackery Lystedt Law?

It is a law enacted in May 2009 that is named after a 13-year-old football player from Washington who suffered a debilitating brain injury after a concussion. In Zackery's case, the concussion alone was not the issue. Zackery returned to play -- in the same game -- after suffering that concussion, then later collapsed after helping lead his team to victory. He was left permanently disabled as a result of severe brain injury. The state of Washington, at the urging of Zackery's parents, enacted the legislation that requires, among other things, that a licensed health care provider clear a youth athlete before he or she returns to play after a concussion. Oregon passed a similar measure last year called Max's Law, named after Max Conradt, who had suffered a traumatic brain injury at age 17 while playing football in 2001.

In a cooperative effort between the Sarah Jane Brain Foundation and the American College of Sports Medicine, an initiative called the Zackery Lystedt Brain Project was launched Wednesday at the Miami Project to Cure Paralysis at the University of Miami School of Medicine. The goal of the initiative is to encourage all remaining states to enact similar legislation. Seventeen more states already have pending or upcoming legislation this year. An additional 26 states have Zackery Lystedt Brain Project concussion coalitions established and appear to be working toward drafting legislation. Five states -- Alaska, Delaware, Nevada, North Dakota and Wyoming -- do not have known concussion coalitions established. The hope is that when the governors of each state convene in late February at the National Governors Association winter meeting, all states will be on board with the initiative.

What are the myths about concussions?

That concussions are a problem only in football. Although there is a prevalence in football, concussions can occur in any sport. Soccer, hockey and basketball see their share. Dr. Gillian Hotz, director of the concussion program at the University of Miami School of Medicine, includes lacrosse players, divers and cheerleaders among her patients who have suffered concussions.

Concussions also are an issue not only for male athletes. Girls are catching up to boys in just about every area of athletic competition, and this is no different. In a recent study published in the Journal of Athletic Training, girls' soccer had the second-highest concussion rate per exposure -- exposure meaning any single game or practice -- after football. Concussions also can occur entirely outside of sports.

Another myth is that it's not really a concussion if you don't get knocked out. That is 100 percent wrong. The loss of consciousness is not a requirement for a concussion. It is particularly important to be aware of a concussion that yields relatively minor symptoms, because returning to play too soon afterward could result in catastrophic consequences.

What is being done in the field of research?

U.S. Rep. Linda Sanchez, D-Calif., views an older NFL football helmet during a hearing in Detroit in January. The House Judiciary Committee heard from retired players about head injuries in football. AP Photo/Paul Sancya

There is so much that is not yet known about concussions that it is a virtual wellspring for scientific study. Perhaps one of the biggest challenges is appreciating what exactly the brain is subjected to during a concussion because the brain is housed within the skull and is therefore virtually impossible to measure directly. Impact studies have been useful in terms of evaluating the durability of protective headgear, for instance, but they fall short when it comes to identifying the specific effects on the brain.

Dr. Steve Olvey, director of the neuroscience intensive care unit at Jackson Memorial Hospital in Miami and a fellow of the FIA Institute of Motor Sport Safety in Paris, believes that the next big wave of data will come from studies using accelerometers implanted in earpieces that can measure what forces the head is subjected to during violent impacts. The accelerometers, which can record information such as g-forces, serve much like little black box recorders that capture crash data in motorsports. By placing them within the earpieces used for communications, they are small enough to go unnoticed by an athlete, yet their position within the ear canal gives information from as close proximity to the brain as possible.

This year, all Formula One drivers will wear earpieces with accelerometers implanted in them. Olvey says that perhaps there will eventually be enough data on the forces that brains are subjected to in various sports to establish some sort of threshold for brain injury. Olvey also stressed the need for equipment differences between youth athletes and adults, specifically in the area of helmets, and noted that adult athletes might return to play after a concussion sporting a larger and heavier helmet that could tolerate impact better. But that might not be a wise choice for athletes under age 18. "Kids' necks are not as well developed," he said, "and bigger, heavier helmets may be problematic."

Is there anything people agree on when it comes to concussions?

If there's anything that's clear about concussions, it's that there is still far more to learn. There are very few absolutes in this area of medical practice, making it challenging for everyone -- parents, coaches, medical providers and athletes. Sports is an important part of a full life, and better management of sports-related injuries, including concussions, ensures a better overall sports experience. What we do know is that common sense and a conservative approach are the wise choice, especially when it comes to youth athletes. As the simple phrase from the Zackery Lystedt Law reads, "When in doubt, sit them out."

Stephania Bell is a physical therapist who is a board-certified orthopedic clinical specialist and a certified strength and conditioning specialist. She is a clinician, author and teacher with extensive experience in the area of orthopedic manual therapy and sports medicine. Her primary patient population consists of athletes and performing artists ranging from junior high school to professional.